Study On The Theory Of Quantum Secret Sharing Protocol

Secret sharing is a method protecting private information by splitting it into several shares. Each share-holder possesses one share, and the secret cannot be recoverd unless the share-holders collaborate with each other. Quantum secret sharing is an important type of quantum cryptography protocol which utilizes quantum effects to realize secret sharing. The quantum physics law guarantees the security of protocol. Quantum secret sharing is an important research field in quantum cryptography. Because quantum cryptography provides with unconditional security and the ability of detecting eavesdropping, it has the very important strategic significance and tremendous prospect in applications. Quantum secret sharing can protect not only classical information but also a quantum one. We have divided quantum secret sharing into quantum secret splitting and quantum secret recovery, given the operating stage. The present quantum secret sharing schemes are of quantum secret splitting schemes in some sense, which ignore a secure recovering mechanism.Based on the National Natural Science Foundation of China under Grant and the Research Project of National University of Defense Technology, we study the theory of quantum secret sharing focusing on the frontier research of this field. According to its operating stage, we proposed some new quantum secret sharing protocols, and analyse the security in detail in the dissertation.Based on W state, we proposed a multiparty quantum secret splitting protocol of secure direct communication, which can share a determinate message between dealer and share-holders. We simplified the eavesdropper checking method by perform determinate quantum measurement. As W state's feature, the protocol holds a robust feasibility in noisy quantum channel.Based on GHZ state, we designed a verifying protocol which can check the correctness of shares after splitting the secret by the dealer without the need of showing the share-holder's shares.We put forward the definition of quantum secret recovery, and designed a quantum secret recovery protocol using even-particle GHZ state without leaking the shares. Applying this protocol, we can recover the secret securely and use the shares repeatedly. The security of the protocol is based upon order rearrangement of entangled particles and entanglement coherence. All of the protocols above we have proposed are secure in noisy quantum channels.